Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
17 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
JavaScript Microtask & Promise Execution Order Debugging
A deep dive into debugging broken promise execution order and microtask queue race conditions in Node.js and browser environments.
Debugging TypeScript .d.ts Declaration File Errors
A practical guide to diagnosing and fixing errors in TypeScript declaration files, covering common pitfalls with third-party types, custom declarations, and compiler issues.
TypeScript strictNullChecks 'possibly undefined' Error: A Debugging Guide
Practical debugging guide for TypeScript's strictNullChecks 'Object is possibly undefined' errors. Covers real-world causes, quick diagnosis, and fixes beyond the obvious.
TypeScript Path Alias 'Cannot Find Module' Errors
A practical guide to diagnosing and fixing 'Cannot find module' errors when using TypeScript path aliases in tsconfig.json.
Debugging TypeScript Conditional Types: Infer Not Firing Correctly
A focused guide on why `infer` in conditional types produces unexpected `never` or wrong types, with concrete diagnostic steps and fixes.
JavaScript Generator Iterator Not Working: Debugging Silent Failures
A hands-on guide to debugging JavaScript generators that fail silently, produce unexpected values, or skip iterations. Covers advanced edge cases like premature return, error swallowing, and iterator protocol violations.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Profiling SQL Queries: Finding and Fixing the Slow 5%
Profiling SQL queries is more than running EXPLAIN. This guide covers practical techniques to find the slowest queries, interpret execution plans, and fix them — with real examples from PostgreSQL and MySQL.
Debugging Character Encoding Problems: From Gibberish to Unicode
A practical guide to identifying and fixing character encoding problems, from broken UTF-8 to hidden BOM bytes, with real debugging examples.
Debugging Timezone Date Bugs: A Case Study in UTC vs. Local Time
A practical walkthrough of a timestamp bug that broke a billing system, with reproducible code and debugging tactics.
Floating Point Arithmetic Errors: A Debugging Postmortem
How a $0.0000000000000004 error silently corrupted a financial system, and the debugging techniques that caught it.
Why JSON.parse() Throws and How to Catch It: A Field Guide to Parsing Failures
JSON.parse() seems simple until it throws. Here's a practical guide to the most common — and most maddening — parsing failures I've encountered, with exact error messages and fixes.
Debugging Third-Party API Issues: A Systematic Approach
A practical guide to diagnosing and fixing third-party API integration problems, with real-world examples and a step-by-step debugging framework.